Concord, NC (Sports Network) - NASCAR's new Sprint Cup Series car is getting rave reviews following the first day of open testing on Tuesday at Charlotte Motor Speedway.

Sixteen teams representing all three auto manufacturers currently in the series -- Chevrolet, Ford and Toyota -- are participating in the two-day session to familiarize themselves with the sixth generation or "G6" race cars for the 2013 season. Several teams did not have opportunity to test the car prior to the end of the season.

"Late in the season, there was a number of teams that either didn't have cars or parts and pieces or they were pretty deep in the Chase (for the Sprint Cup championship), so in fairness to them, we thought that it would be a good opportunity to get in a couple of days out here for those teams that were concentrating on their season," NASCAR vice president of competition Robin Pemberton said.

Dale Earnhardt Jr., who was recently voted as the "most popular driver" in NASCAR's premier series for the 10th consecutive season, gave the car high marks after driving it for the first time.

"It's the first time that I've driven the car, and I'm really impressed," Earnhardt Jr. said. "I really like the balance of the car, and the downforce seems to be relatively good. The car has driven well for us today, and we'll just move through the next couple of days here. We'll keep tuning it and see what it likes and doesn't like."

Making his debut with Joe Gibbs Racing, Matt Kenseth also had a favorable impression of the car. He will drive the No. 20 Toyota for JGR next season following his past 13 years with Roush Fenway Racing. Kenseth's No. 20 team was forced to make an engine change after he over-revved the engine during the morning session.

"I'll be honest, that was probably the first time I was nervous in a race car, getting in there and going out there for the first time, in as long as I can remember," Kenseth said. "It's always exciting, but you're a little anxious when you do something different. It's been fun so far."

Just three weeks after winning his first Sprint Cup championship, Brad Keselowski is getting prep time in a Ford. Penske Racing has switched from Dodge to Ford for the upcoming season.

"It's hard to get a great read on the whole manufacturing change, because it's a different car," Keselowski said. "I think all the signs are there that we have the potential to be just as strong if not stronger than we were (this past season), which is very, very encouraging."

Keselowski also spent time with his new teammate, Joey Logano, who will drive the No. 22 Ford for Penske.

"It's been a lot of fun on the first day today working with Joey, which I think has been probably more of an adjusting process than the actual car itself," Keselowski added. "I'm curious to see over time how we can work together and push each other to be the best that we can be."

Jeff Burton topped the speed charts in the morning with a lap at 190.833 mph in his No. 31 Richard Childress Racing Chevrolet. Regan Smith, who was driving Jeff Gordon's No. 24 Hendrick Motorsports Chevrolet, had the quickest lap during the afternoon session at 190.215 mph. Smith is running a full-time schedule for Earnhardt Jr.'s Nationwide Series team next year.

Testing at Charlotte concludes on Wednesday.

More testing of the car is scheduled for Jan. 10-12 at Daytona and the following week at Charlotte. NASCAR has also made plans for an extra day of testing before the spring races at Las Vegas and Texas as well as extra practice time for the March event in Fontana, Calif.

"It's been said already there are a some things that we still continue to work on, but they are all in a positive note," Pemberton said. "We're taking feedback (from teams) on the downforce and how the cars drive. So the bulk of the work is done, with spoiler sizes and splitters and things like that."

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